Brush to "Spawn" Several meshes on surface?
Join both of the planes that make the grass into a single object.



On the ground plane create a particle system. On the render section select object and assign the grass as Dupli Object.

Make sure the emitter start and end is 1 and the lifetime is as long as the animation you want to make.
Disable gravity. Make the particle size 1 and give it some randomness.

If your grass comes out flat to the ground just enable the rotation box.





sample file here: